The distance the pendulum disc hangs from the clock movement determines how fast or how slow your clock will run. The distance can be shorten or lengthened by turning the nut which is located below the pendulum disc. To make your clock run faster, turn the nut to right. To make your clock run slower turn the nut to left.

One complete revolution of the adjustment nut equals 1 minute per 24 hours.

You should break up the process in 24 hour blocks by using the formula below, should help.

First Day

Set time, wait 24 hours.

Second Day

Compare time

Make adjustment

Reset time

Wait 24 hours

Third Day

Repeat day 2

Wait 24 hours

Many things will make the clock change its timing. Different temperatures, humidity, oil and dirt that's why most pendulum clocks have a way to adjust the length.

French clocks generally have two different ways to adjust the time on the same clock. One is for the major adjustments which is the length of the pendulum. They will also have a second adjustment which you would use a key. There will be a post either above the 12 or below the center shaft where you will turn to the F for faster or the S for slower.